U.S. patent application number 11/993590 was filed with the patent office on 2010-06-24 for axial backlash-adjusted transmission element.
Invention is credited to Hans-Juergen Oberle, Franz Schwendemann.
Application Number | 20100154574 11/993590 |
Document ID | / |
Family ID | 37232908 |
Filed Date | 2010-06-24 |
United States Patent
Application |
20100154574 |
Kind Code |
A1 |
Oberle; Hans-Juergen ; et
al. |
June 24, 2010 |
AXIAL BACKLASH-ADJUSTED TRANSMISSION ELEMENT
Abstract
The invention relates to a transmission drive unit which
comprises a shaft (2) and a housing component (5), an adjusting
element (4) for adjusting the axial backlash of the shaft (2) being
arranged between one end of the shaft (2) and the housing component
(5). The invention is characterized in that the adjusting element
has a substantially cylindrical shape and can be expanded in the
radial direction, when pretensioned, in order to enlarge an outer
diameter, thereby allowing to exert a pretension (F.sub.R) onto the
shaft (2) in the axial direction (X-X).
Inventors: |
Oberle; Hans-Juergen;
(Rastatt, DE) ; Schwendemann; Franz; (Ottersweier,
DE) |
Correspondence
Address: |
MICHAEL J. STRIKER
103 EAST NECK ROAD
HUNTINGTON
NY
11743
US
|
Family ID: |
37232908 |
Appl. No.: |
11/993590 |
Filed: |
August 14, 2006 |
PCT Filed: |
August 14, 2006 |
PCT NO: |
PCT/EP06/65248 |
371 Date: |
December 21, 2007 |
Current U.S.
Class: |
74/409 |
Current CPC
Class: |
F16H 2057/0213 20130101;
F16C 25/04 20130101; Y10T 74/19623 20150115; F16C 27/08 20130101;
F16C 17/08 20130101; F16F 1/04 20130101; F16H 57/12 20130101; F16H
55/24 20130101 |
Class at
Publication: |
74/409 |
International
Class: |
F16H 57/12 20060101
F16H057/12 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 26, 2005 |
DE |
10 2005 045 919.6 |
Claims
1. A transmission drive unit that includes a shaft (2) and a
support component (5), with a compensating element (4) for
compensating for axial backlash of the shaft (2) located between
one end of the shaft (2) and the support component (5), wherein the
compensating element (4) has a substantially cylindrical shape and,
in the pretensioned stated, may be expanded in the radial direction
in order to increase an outer diameter and exert a preload force
(F.sub.R) on the shaft (2) in the axial direction (X-X).
2. The transmission drive unit as recited in claim 1, wherein a
readjustment force (F.sub.N) of the compensating element (4) is
perpendicular to the axial direction (X-X) of the shaft (2).
3. The transmission drive unit as recited in claim 1, wherein the
compensating element (4) is a spiral.
4. The transmission drive unit as recited in claim 3, wherein the
compensating element (4), which is designed as a spiral, is formed
of a flat metal band or spring wire and includes at least two
windings.
5. The transmission drive unit as recited in claim 4, wherein
adjacent windings are in contact with each other.
6. The transmission drive unit as recited in claim 3, wherein the
spiral includes an outwardly directed positioning region (4a) that
bears against the support component (5).
7. The transmission drive unit as recited in claim 6, wherein the
support component (5) includes a recess (8) or a projection against
which the positioning region (4a) of the compensating element (4)
bears.
8. The transmission drive unit as recited in claim 1, wherein the
compensating element (4) is a cylindrical spring.
9. The transmission drive unit as recited in claim 1, characterized
by a stop element (9) with a stop surface (9a), the stop element
(9) being located on a side of the compensating element (4)
directed toward the shaft (2), and the stop surface (9a) being
located at an angle (.alpha.) to a central axis (X-X) of the shaft
(2), the angle (.alpha.) being not equal to 90.degree..
10. The transmission drive unit as recited in claim 1, wherein a
thrust washer (6) is located between an end of the shaft (2) and
the compensating element (4).
11. The transmission drive unit as recited in claim 1, wherein a
transmission component (3) is located on the shaft (2).
12. The transmission drive unit as recited in claim 1, wherein the
shaft (2) is an armature shaft of an electric motor.
Description
RELATED ART
[0001] The present invention relates to a transmission drive unit
with compensation of axial play of a shaft.
[0002] To prevent or adjust the axial play of shafts in adjusting
motors or transmissions, such as spindle transmissions, the axial
forces that occur during operation may result in shaft play. This
play should be prevented to the greatest extent possible.
Prevention of axial play is preferably designed such that it
continues for the duration of the service life of the component,
even if wear occurs. Publication DE 101 14 453 A1 makes known,
e.g., a transmission drive unit with which compensation of axial
play of a shaft is attained using damping means located on the
outer circumference of a pot-shaped sleeve element. The end of the
shaft is positioned in the pot-shaped sleeve element.
[0003] Other known possibilities for compensating for axial play
are, e.g., to provide an adjusting screw that is located coaxial
with the shaft and may be adjusted until the axial play of the
shaft has been eliminated. It is also known to locate compensating
washers between an end of the shaft and a support component, the
compensating washers being selected from a large number of
compensating washers of different thicknesses, depending on the
amount of axial play that the shaft has. A large number of
different compensating washers must be kept on hand, however.
ADVANTAGES OF THE INVENTION
[0004] In contrast, the inventive transmission drive unit with the
features of Claim 1 has the advantage that it may provide
self-adjusting compensation of axial play. The compensation of the
axial play of the shaft may be ensured for the duration of the
service life of the transmission drive unit, in the new state and
if use-induced wear occurs. According to the present invention,
therefore, a large number of compensating washers of different
thicknesses need not be kept on hand, and complicated procedures to
measure the axial play in order to select the correct compensating
washer may be eliminated. This is attained according to the present
invention by providing a compensating element for compensating for
axial play, the compensating element being located between the
start-up rail and a support component, e.g., a housing part, the
compensating element having an essentially cylindrical shape and
being expandable in the radial direction. The compensating element
may therefore exert a preload force on the armature shaft in the
radial direction. The essentially cylindrical compensating element
is therefore located between the shaft and a housing component in
such a manner that the axial direction of the shaft is
perpendicular to the axial direction of the essentially cylindrical
compensating element.
[0005] The subclaims show preferred refinements of the present
invention.
[0006] A readjustment force of the compensating element is
preferably perpendicular to an axial direction of the shaft and/or
to an axial force that acts on the shaft. As a result, the axial
force acting on the shaft and the readjustment force of the
compensating element are prevented from affecting each other,
thereby preventing the shaft from being lifted by the readjustment
force of the compensating element, e.g., if no axial force acts on
the shaft.
[0007] Particularly preferably, the compensating element is a
spiral. The spiral is preferably made of a metal material and may
be drawn together radially to be tensioned. When the spiral is
tensioned, an outer diameter is reduced in particular, thereby
making assembly particularly simple and easy. Once the spiral has
been installed, the loaded spiral may be simply released. Due to
its inherent elasticity, the spiral attempts to return to its
initial, unloaded state, and its outer diameter increases. A
self-adjusting compensation of axial play using the spiral is
therefore made possible in a simple manner.
[0008] According to a preferred embodiment of the present
invention, the spiral is formed of a flat metal band and includes
at least two windings. The windings are designed such that they are
in contact with each other. Friction therefore occurs between the
individual windings, thereby making it possible to provide a
greater radial force to the spirals.
[0009] To ensure that the spiral is positioned correctly, the
spiral preferably includes an outwardly extending positioning
region that bears against the support component, or the like. The
positioning region of the spiral is preferably located in a recess
in the support component, or it bears against a projection formed
on the support component.
[0010] According to another preferred embodiment of the present
invention, the compensating element is a spiral spring made of
spring wire. It may be provided in a particularly easy and
cost-favorable manner.
[0011] Also preferably, a stop element with a stop surface is
provided, the stop element being located on a side of the
compensating element directed toward the shaft. The stop surface is
located at an angle not equal to 90.degree. with a central axis of
the shaft.
[0012] The compensating element is preferably a cylindrical spring
made of spring wire.
[0013] Also preferably, a thrust washer is located between an end
of the shaft and the compensating element. According to the present
invention, by using the compensating element, a thrust washer with
a predetermined thickness may be used without the need to stockpile
a large number of different thrust washers so that the compensating
element may compensate for axial play that may be present.
[0014] The inventive transmission drive unit is preferably an
electrical machine with a transmission part located directly on the
armature shaft, e.g., a wormwheel. The electrical machine is
preferably designed as an electric motor and is preferably used in
comfort and convenience drives of motor vehicles, such as power
windows, power sunroofs, electrical seat adjusters, etc.
DRAWING
[0015] Exemplary embodiments of the present invention are described
in detail below with reference to the attached drawing.
[0016] FIG. 1 shows a schematic top view of a transmission drive
unit according to a first exemplary embodiment, during
assembly,
[0017] FIG. 2 shows a schematic sectional view along the line A-A
in FIG. 1,
[0018] FIG. 3 shows a schematic top view of the transmission drive
unit in FIG. 1, in the assembled state,
[0019] FIG. 4 shows a schematic sectional view along the line B-B
in FIG. 3,
[0020] FIG. 5 shows a schematic top view of the transmission drive
unit in FIG. 1, when wear occurs,
[0021] FIG. 6 shows a schematic sectional view along the line C-C
in FIG. 5,
[0022] FIG. 7 shows a schematic top view of a transmission drive
unit according to a second exemplary embodiment of the present
invention, and
[0023] FIG. 8 shows a sectional view of a transmission drive unit
according to a third exemplary embodiment of the present
invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0024] A transmission drive unit 1 according to a first exemplary
embodiment of the present invention is described below with
reference to FIGS. 1 through 6.
[0025] Transmission drive unit 1 includes an electric motor with a
shaft 2, on which a wormwheel 3 is located. Shaft 2 is the armature
shaft of the electric motor. As shown in FIG. 2 in particular, a
ball 7 or a spherical axial stop that may be designed, e.g., as a
cap and forms a punctiform axial bearing is located on the end of
the shaft.
[0026] Shaft 2 is located in a housing component 5. In addition, a
compensating element 4 is provided to compensate for axial play of
shaft 2 in axial direction X-X of shaft 2. Compensating element 4
is located between a thrust washer 6 at the end of shaft 3--which
is formed by ball 7 in this exemplary embodiment--and housing
component 5. Housing component 5 serves as a support component for
the compensating element. As shown in FIG. 1 in particular, a
recess 5c with a first support surface 5a and a second support
surface 5b is formed in housing component 5. First support surface
5a is perpendicular to second support surface 5b.
[0027] Compensating element 4 is a spiral made of a flat metal
band. As shown in FIG. 1, compensating element 4 includes an
outwardly directed positioning region 4a and an inwardly directed
preload region 4b. Positioning region 4a and preload region 4b are
both formed by one end of the flat band material. Compensating
element 4 is essentially cylindrical in shape. Compensating element
4 is positioned relative to shaft 2 such that its axial direction
Y-Y is perpendicular to axial direction X-X of the shaft (see FIG.
2).
[0028] Compensating element 4 is capable of applying a radial force
F.sub.R, which acts in axial direction X-X of shaft 2 (see FIG.
3).
[0029] A thrust washer 6 is located between ball 7 and compensating
element 4. In the installed state, thrust washer 6 is clamped
between the end of shaft 2 and compensating element 4. A recess 8
is formed in housing component 5, in which positioning region 4a of
compensating element 4 is located. Recess 8 therefore simplifies
assembly and ensures that compensating element 4 is always
positioned correctly.
[0030] FIG. 1 shows the compensating element in the assembled
state. For assembly, compensating element 4 is rolled together
around preload region 4b and is pretensioned, with a tightening
torque M.sub.A being applied to compensating element M.sub.A. As
shown in FIG. 1, the tightening torque is exerted in the clockwise
direction. As a result, an outer diameter of compensating element 4
is reduced from a starting state, in which compensating element 4
was unloaded, to outer diameter D1. Compensating element 4 is
preferably preloaded when compensating element 4 is located in
housing 5, since positioning region 4a is then already located in
recess 8. This simplifies the procedure for preloading the
compensating element. When compensating element 4 is preloaded as
shown in FIG. 1, thrust washer 6 may be easily inserted between
shaft 2 and compensating element 4. It should be noted that, with
regard for the assembly procedure, it is also possible to install
thrust washer 6 first, of course, without compensating element 4
having been installed, and to preload compensating element 4
outside of transmission drive unit 1, so that it has a small
diameter D1 and is then installed.
[0031] When all components of transmission drive unit 1 are
installed, the preload is removed from compensating element 4, so
that the tension on it is released. A result, a radial force
F.sub.R is exerted on thrust washer 6, and thrust washer 6 is
pressed against ball 7 of shaft 2 (see FIG. 4). The outer diameter
of compensating element 4 increases to D2, as shown in FIG. 3. As a
result, compensating element 4 exerts a constant preload force on
thrust washer 6 and, therefore shaft 2. Compensating element 4
bears against first and second support surfaces 5a, 5b of housing
component 5. As tension is released from compensating element 4, a
nominal torque M.sub.N is produced, thereby causing a readjusting
force F.sub.N to be exerted on compensating element 4. Readjusting
force F.sub.N acts tangentially on the contact point between
compensating element 4 and thrust washer 6. An axial force F.sub.A
that may act on shaft 2 is therefore perpendicular to readjusting
force F.sub.N (see FIG. 3). As a result, in particular, shaft 2 is
prevented from being lifted due to the preload force of
compensating element 4 when an axial force F.sub.A is applied to
compensating element 4. Compensating element 4, which is
essentially cylindrical in shape, also enables installation space
to be optimized, since the radial preload force is provided via a
rotational motion of compensating element 4.
[0032] When long-term operation results in components becoming
worn--which affects the axial length of the components in
particular--inventive compensating element 4 may automatically
compensate for the axial play. Wear V on thrust washer 6 is shown
in FIGS. 5 and 6 as an example. Without inventive compensating
element 4, axial play in the amount equivalent to wear V would
result. Due to wear V, compensating element 4 continues it
rotational motion, however, and the outer diameter of compensating
element 4 increases to D3, with D3=D2+V. As a result, play is
eliminated between the components in axial direction X-X of the
shaft.
[0033] As revealed in a comparison of FIGS. 1, 3 and 5,
compensating element 4 is therefore preloaded in the clockwise
direction and relaxes in the counterclockwise direction via the
increase in its diameter. This is also indicated by the respective
position of preload region 4b shown in FIGS. 1, 3 and 5. The
increase in the outer diameter of the compensating element always
generates a radial force F.sub.R that acts in direction X-X, which
compensates for any play in transmission drive unit 1 that may
result due to wear.
[0034] Since compensating element 4 is made of a flat material that
has been rolled up, friction occurs between the individual windings
that are in contact with each other, so that a sufficient amount of
radial force F.sub.R may be applied to shaft 2 in every
position.
[0035] To ensure reliable functioning of compensating element 4 for
the duration of the service life of the transmission drive unit,
compensating element 4 therefore need only be preloaded in such a
manner that an increase in its outer diameter may compensate for
tolerances in the new state, and for the maximum wear that may
occur.
[0036] A transmission drive unit 1 according to a second exemplary
embodiment of the present invention will be described below with
reference to FIG. 7. Parts that are identical or that perform the
same function as those in the first exemplary embodiment are
labelled with the same reference numerals as in the first exemplary
embodiment.
[0037] The second exemplary embodiment is essentially the same as
the first exemplary embodiment, with the difference that a stop
element 9 is provided. Stop element 9 includes two wedge-shaped
ramps that are located on thrust washer 6. Stop element 9 includes
stop surfaces 9a, which are located at an angle .alpha. to central
axis X-X of shaft 2. Angle .alpha. is approximately 60.degree.. By
providing the stop element, the number of force application
points--which are indicated with arrows F in FIG. 7--is increased
to four. Since stop element 9 is located on thrust washer 6, it
must be ensured that thrust washer 6 is installed in transmission
drive unit 1 with the correct orientation.
[0038] FIG. 8 shows a transmission drive unit 1 according to a
third exemplary embodiment of the present invention. Parts that are
identical or that perform the same function as in the preceding
exemplary embodiments are labelled with the same reference numerals
as in the preceding exemplary embodiments.
[0039] The difference between the third exemplary embodiment and
the first exemplary embodiment is that a cylindrical spring made of
spring wire is provided as compensating element 4. As with the
spiral shown in the first exemplary embodiment, the cylindrical
spring may be preloaded by applying a certain amount of torque to
the wire, so that an outer diameter of the cylindrical spring is
reduced. The change in the outer circumference depends, in
particular, on the type of wire, the number of windings, the
stiffness of the wire, the thickness of the wire, etc. Compensating
element 4 is installed with cylinder axis Y-Y perpendicular to
axial direction X-X and is installed in the preloaded state and
then released, so that a continual radial force may be applied to
thrust washer 6. Otherwise, this exemplary embodiment is the same
as the first exemplary embodiment, so reference is hereby made to
the description provided therefor.
* * * * *